Submitted to: Nitrogen
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/4/2024
Publication Date: 6/6/2024
Citation: Gregg, S., Gesch, R.W., Garcia Y Garcia, A. 2024. Nitrogen uptake and use efficiency in winter camelina with applied N. Nitrogen. 5:509-517. https://doi.org/10.3390/nitrogen5020033.
DOI: https://doi.org/10.3390/nitrogen5020033

Interpretive Summary: Winter camelina is an alternative oilseed crop that can help diversify upper Midwestern cropping systems by growing it during the fallow period between summer annual crops like corn and soybean. Winter camelina can scavenge excess nitrogen left unused in the soil by a previous crop, thus reducing potential off-site movement of nitrogen that can contaminate water and air. However, little is known about nitrogen uptake and use efficiency for growth and grain yield of winter camelina. This study was conducted across three different sites in Minnesota to determine soil nitrogen uptake and various nitrogen use indices of winter camelina fertilized at different rates of nitrogen ranging from 0 to 120 lbs/acre that was applied in either the fall or spring. Nitrogen agronomic, internal, and recovery efficiency all tended to decrease with increased nitrogen fertilizer rate, especially over 60 lbs/acre. Total plant nitrogen uptake ranged from 30 to 157 lbs/acre, which was as much as four times higher than the applied rate of nitrogen. This result indicates that there was additional plant uptake of mineralized nitrogen present in the soil. Because of declining nitrogen use efficiency with increased fertilizer rate, it is recommended to apply no more than 60 lbs/acre of nitrogen fertilizer in the spring to reduce the environmental risk that could occur from adding too much. This information will help refine fertilizer recommendations for winter camelina and benefit farmers and ag professionals interested in producing it as an oilseed crop.

Technical Abstract: Maize (Zea mays L.) and soybean [Glycine max (L.) Merr.] rotations in the upper Midwest are highly productive, but decades of these narrow rotations with a long winter fallow are partly responsible for the loss of agroecological functioning such as increased ground water pollution from nitrate-nitrogen. Winter camelina [Camelina sativa (L.) Crantz] is a third crop that could grow during this fallow period, but its N uptake and use efficiency are not well known. A study was conducted at three locations in Minnesota to determine N uptake and use efficiency of winter camelina in response to applied nitrogen (N) and N application timing. Agronomic efficiency (AE), internal efficiency (IE), and nitrogen recovery efficiency (NRE) tended to decrease with increasing N rates, especially beyond 67 kg N ha-1 in most instances. Total N uptake ranged from 34 to 176 kg ha-1 across N rates, which was as much as four times the applied rate. Based on declining NUE with increasing N rates, a N rate of 67 kg ha-1 could balance efficient fertilizer use with lower environmental risk compared to higher N rates.